Zs. P. Komáromy szerk.: Studia Botanica Hungarica 16. 1982 (Budapest, 1982)

Hably, Lilla: The relation between Pb-pollution along mainroads and the trace element-composition in soil and vegetation (Examination of section rectangular to M3 mainroad)

cm. The chemical effect of the soil is never acidic within the section, it is alkolescent with pH values between 7.5 and 8.5. The organic content of the section is the highest in the layer between 20 and 40 cm, hardly exceeding 3%. The organic material content is the smallest in the lowest layer as well as in the layer between 100 and 120 cm, where it is between 1.7-1.8%. Clay mineral contents (Illite) increases first in the layer between 40 and 60 cm, then with slight recession it reaches the value of 36% similar to the above, between 80 and 100 cm. Between 160 and 180 cm there is a remarkable recession, then under this in the lowest sample of the section the Illite-content reaches its maximum in the section. The upper 60 cm of the section contains no demonstrable quantity of carbonate minerals. In the sample between 60 and 80 cm less than 2% carbonate mineral has been measured. It is missing again in the next 20 cm layer, then its quantity increases reaching its maximum about 14% between 160 and 180 cm. After that slight decrease can be seen. Of the trace elements the changes of the soluble quantities of manganese, zinc, copper and lead were examined. Manganese is present in the largest quantity. Its concentration is greater by one or two as related to the corresponding value of copper and lead and three in relation to zinc, magnitude. The soluble trace element content shows a decreasing tendency for all the elements examined. In addition to Mn, Pb, and then Cu can be found in greatest quantitites. Zn is present in the smallest quantity. Its soluble concentration is significantly higher in the highest layer than in the lower layers. In the middle layers between 80 and 100 cm, remarkable increase of soluble element contents can be observed which in case of Mn and Cu approximates the value of the first layer, but remains under this value in case of Pb and Zn. Section No.

31 (Fig. 3) The A-level of the soil-section is in the upper 20 cm, followed by B-level down to 140 cm. The chemical reaction of the soil never falls within the acidic interval. In the upper layer the pH is almost neutral (7.25), which shows a regular and gradual increase downwards. It reaches its maximum 8.4 pH value at a depth of 160 cm under which the pH was found constant to the bottom of our section. The changes in organic material contents can be called also relatively constant, its maximum 4.2% is in A-level, with unmistakable decrease from there on. It shows a slight increase in the layer between 60 and 80 cm which, however, is far from the one, seen in the first two layers. The clay mineral content of the section is rather variable, alternating between 21% and 34%. The Illite content of the part between 160 and 180 cm is the highest. It reaches a constant value of 30% in the lower part of the B-level. In the layer between 60 and 80 cm, where the increase of organic material can be seen, the quantity of Illite considerably devreases. This tendency characterizes the whole of the section i.e. where there is a decrease in organic material, the Illite content increases. The CaCOß-content of the soil gradually increases after the upper third (60 cm) of the B-level until its maximum of 13%, which it reaches in the layer between 160 and 180 cm. It is present in the A-level only in very small quantity and it can not be seen at all in the next 40 cm. The soluble Mn, Zn, Cu, Pb content, like in the previous section, shows an unmistakable decrease towards the deeper layers. Each reaches its maximum in the A-level. Cu decreases the most evenly, unlike Zn and Pb. The concentration of both of these elements decreases to a great extent after the first level, while the decrease of Mn becomes gradually less and less in the upper 80 cm-s and shows a sudden drop after that. It remains on this low level further on with the exception of its new but small increase between 140 and 160 cm. Section No. 32 (Fig. 4) The A-level of the section is from 0-20 cm, its B-level to 120 cm. The chemical reaction of the soil changes within a much wider interval than so far. The A-level is characterized by a mild acid almost 6 pH, then in the next 40 cm it is near neutral but still under pH 7. At 60 cm the pH changes from acidous into alkaline and from here its even increase can be observed. At its highest point - between 160 and 180 cm -, it almost reaches the value of pH 8.5. Organic material contents of the section reaches its near 5% maximum in the A-level. After that it shows a very quick decrease until under B-level, where it reaches its minimum. After that between 140 and 160 cm it increases again to about the level of the value between 60 and 80 cm, then it decreases again. The Illite reaches its minimum in the A-level, after that its quantity suddenly